How do cyclones work?

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A cyclone is a rotating vortex of air caused by thermal currents around a low-pressure center. Tropical cyclones are enormous storms that rotate around a vertical axis, driven by warmth and moisture from tropical ocean waters. Tornadoes and land-based cyclones occur when unstable winds create rotation in the upper levels of a storm, and a strong downdraft pulls the vortex down to touch the ground.

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Both types of cyclone are driven by differences in temperature at various levels of the atmosphere. In a tropical cyclone, warm low level air rises into cooler regions above, allowing moisture to condense out of it before it falls back to the ocean's surface. Meanwhile, winds blow into the center of the low pressure zone created by this rising air, eventually giving the storm rotational motion due to Earth's Coriolis effect.

Mesocyclones and tornadoes occur when fronts overlap, causing unpredictable variations in the wind called wind shear. Strong wind shear can cause the air high up in clouds to spin, creating a rotation that draws energy from the surrounding storm. When the vortex descends from the clouds, it wraps itself in moisture, creating the cone-shaped silhouette of a tornado. Since these storms have no way to refresh their energy, they tend to dissipate very quickly, but they can do enormous damage before falling apart.